1. Field of the Invention
This invention relates to visible light communication system and, more particularly, to using remote control devices with cameras to communicate with controlled devices using visible light.
2. Description of Related Art
Remote controllers have become ubiquitous for controlling all sorts of electronic components including TVs, sound systems, ceiling fans, projectors, computers, thermostats, lighting systems, etc. However, each remote controller is typically unique for the particular associated electronic device. Universal remote controllers have had some success combining functions in one handheld device; however, they are expensive, cumbersome, and subject to being lost.
Remote control can be useful for a number of different reasons. The most common advantage is being able to change channels on a TV set without having to move from the comfort of a chair or couch. Another advantage is being able to control a device, such as a light or ceiling fan that may be attached to a high ceiling and out of reach. Another advantage is that having a remote controller can reduce the size and complexity of the device being controlled. For instance, the remote controller can have multiple buttons and indicators or even a touch screen and computer for controlling the device. This can enable the controlled device to simply be configured to send and receive wireless data.
Remote controllers can communicate using a variety of wireless communication protocols, but typically use infrared light or radio frequency (RF) electromagnetic radiation based physical layers. For example, many commercial and residential lighting systems have remote controllers that enable lights to be controlled locally. However, these remote controllers typically use infrared physical layers, which require the light fixtures to have infrared transceivers. This inevitably increases the cost of the lighting control system.
Some lighting control systems have been introduced that use visible light communication (VLC) to communicate optical data to light fixtures or other devices. Lighting control systems that use VLC have many advantages over conventional lighting control systems that use infrared remote controllers and transceivers, or employ other types of wired and wireless communication protocols. One big advantage is that the visible light spectrum is currently globally unregulated, and does not suffer from the congestion and interference common in RF-based communication systems. Another advantage is cost savings.
For example, light fixtures controlled by visible light do not use infrared transceivers for communicating with infrared remote controllers, and thus, do not incur the costs associated with conventional lighting control systems. In addition, a lighting control system employing visible light communication may transmit optical data using the same light fixture used to provide illumination, e.g., in a room of a building. In the case that the light fixture comprises one or more LEDs, the LEDs can also be used as light detectors for receiving optically transmitted data. Finally, no dedicated wires are needed in a system that transmits optical data using visible light traveling through free space. This is especially important for installation of lighting control systems in existing buildings. These advantages, and possibly others, enable the visible light communication protocol to be implemented within a lighting control system for very little cost.
A limitation of the visible light communication protocol, and specifically, a protocol that transmits optical data using visible light traveling through free space, is that it is typically limited in communication range and generally restricted to line of sight. In other words, optical data transmitted through free space typically cannot be communicated around corners or through walls between various rooms in a building, or between light fixtures and other devices that are too far away and outside of the optical communication range of the remote control device. Therefore, a need exists for a system and method that can extend the communication range in a visible light communication system.